Latino children are at increased risk for poor educational outcomes, scoring below non-Hispanic Whites in reading and math in elementary and secondary grades and dropping out of high school at higher rates. In part, increased risk to Latino children is associated with overrepresentation in poverty. Increased risk is also associated, however, with reduced language support in early educational environments for children who are English Language Learners (ELLs), leading to poor foundational skills and abilities in literacy, math, and social-emotional competence. To address the problem of poor school readiness among ELL Latino children, we propose to test the efficacy of an innovative preschool curriculum known as Tools of the Mind that is designed to enhance language and self-regulation development and promote children's early academic and social-emotional competencies. To evaluate the program, we will conduct a randomized controlled trial involving 400 children in 80 pre-k classrooms in El Paso, TX and Pinellas County, FL. Treatment classrooms will implement Tools of the Mind and control classrooms will implement business as usual approved curricula at each site. We hypothesize that treatment effects will be observed at the end of pre-k in classrooms implementing Tools of the Mind and will be sustained at the end of kindergarten and first grade. We further hypothesize that effects of the Tools of the Mind program on child language development (in both Spanish and English) and on child self-regulation development will partially account for sustained program effects on school achievement through the end of first grade. We recognize, however, that variation in the amount of instruction in Spanish that children in the sample receive will also influence early language development and school outcomes. Accordingly, we include sites in which the language of instruction will be predominantly Spanish (TX) and predominantly English (FL) to test the hypothesis that ELLs who receive predominantly Spanish instruction during pre-k will experience greater growth in their Spanish and English language development and that this will result in higher literacy and math outcomes in kindergarten and 1st grade.